# PyPI (Python Infrastructure): Major incident: PyPI Partial Outage

**Summary:** _summary pending_
- Kind: Major incident · Label: major (vendor)
- Changed: 2025-05-24 23:37 UTC · Detected: 2026-10-19 17:03 UTC
- [Source: https://stspg.io/dcxkgkkx6sj8](https://stspg.io/dcxkgkkx6sj8)
- [Company: PyPI (Python Infrastructure)](https://rewindex.com/company/pypi.md)
- Versions: before (none: first archived) → after incident\_version:669/wtqw8mxcg3j1@26ac2325eeb3
- Change 1 of 1 for this incident

Incident page (full timeline): [PyPI Partial Outage](https://rewindex.com/company/pypi/incidents/wtqw8mxcg3j1.md)
## What changed

**1. Added: Title**

```diff
+ PyPI Partial Outage
```

**2. Added: Impact**

```diff
+ major
```

**3. Added: Status**

```diff
+ resolved
```

**4. Added: Start time**

```diff
+ 2025-05-24 23:37 UTC
```

**5. Added: Resolved time**

```diff
+ 2025-05-27 12:53 UTC
```

**6. Added: Affected components**

```diff
+ pypi.org - Backends, PyPI - pypi.org - Backends
```

**7. Added: Update** (investigating) · 2025-05-24 22:57 UTC

```diff
+ We are working to investigate a partial outage in the PyPI backends.
```

**8. Added: Update** (identified) · 2025-05-24 23:11 UTC

```diff
+ We have identified a large increase in CDN cache misses causing excess load on our backends. We are working to determine the reason for this increase.
```

**9. Added: Update** (identified) · 2025-05-24 23:37 UTC

```diff
+ We have identified a flood of requests from a cluster using the ʹpython-requests/2.32.3ʹ User-Agent, and attempting to hit all JSON project/releasese en masse. This causes excessive cache misses, which are overwhelming our backends. A temporary block has been put in place.
```

**10. Added: Update** (monitoring) · 2025-05-24 23:54 UTC

```diff
+ Our block is in place and systems are stable, but we are not satisfied with having to block such a generic user-agent. If you are aware of a system that began a mass crawl of PyPI's JSON release endpoints starting at around 22:05 UTC 2025-05-25, please contact admin@pypi.org.
```

**11. Added: Update** (monitoring) · 2025-05-25 12:16 UTC

```diff
+ We have removed the temporary block and are continuing to monitor.
```

**12. Added: Update** (resolved) · 2025-05-27 12:53 UTC

```diff
+ We have not seen a return of the traffic that caused this incident after removing the temporary block. We will open a new incident if we need to take action again.
```

## History of this incident

| When (UTC) | Change | Label |
| --- | --- | --- |
| 2025-05-24 23:37 UTC | Major incident: PyPI Partial Outage (this change) | major |

All PyPI (Python Infrastructure) changes: [timeline](https://rewindex.com/company/pypi/changes.md)
_Diff excerpts are shown on normalized text: dates, counters and tokens appear as ‹date›, ‹count›, ‹tok›; noise-only edits are hidden. Rewindex shows the changed passages, not a copy of the page._


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Canonical: https://rewindex.com/change/i7ff07a3ce707ac · Markdown: https://rewindex.com/change/i7ff07a3ce707ac.md · JSON: https://rewindex.com/api/v1/changes/i7ff07a3ce707ac · Generated 2026-10-20T00:00:39.624Z